Rotary pump.



No. 647,951. Patented Apr. 24, I900.

R. C. ENYABT. ROTARY PUMP.

' (Application filed. Oct. 17, 189B.)

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YNITED STATES T PATENT Fries.

RALPH C. EN YART, OF OONNERSVILLE, INDIANA, ASSIGNOR TO THE P. H. & F. M. ROOTS COMPANY, OF SAME PLACE.

ROTARY PU M P.

"srncxmoarroiv forming part of Letters Patent No. 647,951,019tted April 24, 1900.

Application filed October 17,1898. Serial No. 6935699. (Modeh) To ctZZ whom it may concern: 7

Be it known that I, RALPH C. ENYART, of Connersville, Fayette county,Indiana, have invented certain new and useful Improve-- ments in Rotary Pumps, of which the following is a specification.

This invention pertains to that class of ro tary pumps employing a pairof lobed impellers working within an elliptic casing, the

shafts of the impellers being geared together.

either with liquids or fluids.

My improvement has forits object to increase the strength, tightness, smoothnessof working, and durability of such pumps, and theimprovement will be readily understood from the following description, taken in connection with the accompanying drawings, in Which- Figure 1 is a vertical section ofa rotary pump embodying my improvement, while Fig. 2 isa horizontal section of the same, the impellers appearing in plan in the latter view.

In the drawings, 1 indicatesthe usual casing, generally elliptical in cross-section of chamber and having fiat heads and opposite openings for the inflow and outflow of the liquid or fluid, 2, the two parallel impellershafts journaled in the heads and having their axes at the centers of the side arcs of the casing, these two shafts to be arranged for being turnedby power in the usual manner; 3, the two lobed impellers, each fast on its appropriate shaft, the ends of the impellers engaging against the inner faces of the heads of the casing; 4, the outer extremities of the lobes of the impellers, the same being formed by circulararcs struck from the centers of the shafts with a radius equal to the distance from the center of the shaft to the circular arc defining the nearer inner side wall of the casing; 5, the hubs of the impellers surrounding the shafts and extending from head to head of the casing, the diameters of the hubs being substantially equal to the transverse width of the outer extremities of the lobes; 6, the peripheries of the hubs, the

same being formed with convex curves concentric with the shafts; 7, minor convex curves curves joining the convex curves 6 and 7, and

9 chambers extending longitudinally through the lobes for. the'purpose of lessening the weight of theimpellers. It will thus be seen that the extremities of each of the arcs 6, technically known as the waist-arcsj are joined-to the adjacent extremities of the arcs .4, known asthe lobe-arcs, by concave-com vex curves which blend smoothly at their re spective ends with said Waist and lobearcs. Furthermore, it will be observed that the condecreasing radiusfrom the point Where it blends with the waist-arc to the point where it joins the convex portion 7 and that said convex portion 7 is a curve with a constantly decreasing radius from the point where it blends with the lobe-arc to the point-where it joins'said concave portion 8. Thispoint where the curves 7 and 8 join may be conveniently located on the pitch-circle of the im peller and forty-five degrees from the radii passing through the centers of the lobe and waist arcs, respectively. 7

The peculiar form of impeller shown results in a hub of greater diameter, its diameter being substantially equal to the greatest transverse dimension of the impeller,,thus giving great strength at the waist where the the opposing impeller, the contact, once taken up, is continued absolutely progressively and uninterruptedly throughout the period of engagement of that lobe, there thus being a total avoidance of pockets in which liquid or fluid can become entrapped. Machines of this type are used largely, if not mostly, for

' cave portion Sis a curve with a constantlypumping liquids which are incompressible, and if the contacts between the impellers are discontinuous and pockets are formed these pockets are subject to decrease in size, the result being that the incompressible liquid puts the machine under enormous strains and results in destructive hamn1er-blows,putting serious limits upon practical speeds of Working.

In the present construction there is an absence of pocketing and resulting strains and hammer-blows, and high speeds are available in practice. It has heretofore been deemed impossible in rotary pumps to secure extended inwall-contacts along with an absence of pocketing between impellers, and my present machine has opened up possibilities of utilization of rotary pumps not possible under the conditions imposed by the state of the prior art.

What I claim is- In a pump the combination of a pair of parallel shafts, a casing having concave inwalls concentric with said shafts, two similar impellers fast one on each shaft, each of said impellers having oppositely-disposed lobesections bounded by arcs concentric with its shaft and awaist-secti'on also concentric with its shaft and of a diameter substantially equal to the greatest transverse width of the lobes, the extremities of the waist-arcs being joined to the adjacent extremities of the lobe-arcs by a concave-convex curve which blends at its extremities -with said arcs, the concave portion of which curve extends with a constantly-increasing radius from a point on the pitch-circle of the impeller forty-five degrees from the radii passing through the centers of the lobe and waist arcs to the point of blend with the Waist-arc, and the convex portion of which curve extends with a constantly-increasing radius from said point on the pitchcircle to the point of blend with the lobe-arc.

RALPH C. ENYART.

Witnesses:

L. E. BLINN,

W. S. CALDER. 

